Apparatus and method for defining illumination parameters of a sample

ABSTRACT

In one embodiment, the disclosure relates to a method for determining illumination parameters for a sample, the method may include obtaining an absorption band of the sample; obtaining an emission band of the sample and determining the illumination parameters for the sample as a function of the absorption band and the emission band of the sample.

The instant application relates to Application Serial No. ______ filedeven date herewith by the inventors named herein, the specification ofwhich is incorporated herein in its entirety for background information.

BACKGROUND

Spectroscopic imaging combines digital imaging and molecularspectroscopy techniques, which can include Raman scattering,fluorescence, photoluminescence, ultraviolet, visible and infraredabsorption spectroscopies. When applied to the chemical analysis ofmaterials, spectroscopic imaging is commonly referred to as chemicalimaging. Instruments for performing spectroscopic (i.e. chemical)imaging typically comprise image gathering optics, focal plane arrayimaging detectors and imaging spectrometers.

In general, the sample size determines the choice of image gatheringoptic. For example, a microscope is typically employed for the analysisof sub micron to millimeter spatial dimension samples. For largerobjects, in the range of millimeter to meter dimensions, macro lensoptics are appropriate. For samples located within relativelyinaccessible environments, flexible fiberscopes or rigid borescopes canbe employed. For very large scale objects, such as planetary objects,telescopes are appropriate image gathering optics.

Regardless of the type of optical equipment, a first step in anyspectroscopic investigation is defining a suitable wavelength forilluminating the sample. The step of defining an suitable wavelength forilluminating the sample becomes even more important when simultaneousmultiple images of the sample are sought. Conventional methods suggestilluminating a sample with a first wavelengths (e.g., NIR or VIS) toobtain a first image, followed by illuminating the sample with a secondwavelengths to obtain a second image (e.g., Raman or dispersive Raman)to obtain a second image. Consequently, the conventional process aretime consuming and are not suited for simultaneous imaging of the ample.There is a need for a apparatus and method for determining illuminationparameters of a sample a priori of illuminating the sample.

SUMMARY OF THE DISCLOSURE

In one embodiment, the disclosure relates to a method for determiningillumination parameters for a sample, the method including obtaining anabsorption band of the sample; obtaining an emission band of the sample;and determining the illumination parameters for the sample as a functionof the absorption band and the emission band of the sample.

In another embodiment, the disclosure relates to a system for definingillumination parameter for a sample comprising an illumination source,an optical train and a processor programmed with instructions forobtaining an absorption band of the sample; obtaining an emission bandof the sample, the emission band including a lower wavelength range andan upper wavelength range; and determining the illumination parametersfor the sample as a function of the absorption band and the emissionband of the sample.

In still another embodiment, the disclosure relates to a method fordetermining illumination parameters for a sample, the method comprisingsimultaneously illuminating the sample with illuminating photons, theilluminating photons defining a first wavelength and a secondwavelength; obtaining at least one of an emission band and an absorptionband of the sample from the illuminating photons interacting with thesample, the emission band defining a lower wavelength range and an upperwavelength range; and determining the illumination parameters for thesample as a function of the absorption band and the emission band of thesample.

Still another embodiment of the disclosure relates to a system fordefining illumination parameter for a sample comprising an illuminationsource, an optical train and a processor programmed with instructions tosimultaneously illuminate the sample with illuminating photons, theilluminating photons defining a first wavelength and a secondwavelength; obtain at least one of emission band and an absorption bandof the sample from the illuminating photons interacting with the sample,the emission band defining a lower wavelength range and an upperwavelength range; and determine the illumination parameters for thesample as a function of the absorption band and the emission band of thesample.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 graphically illustrates the relationship between intensity andwavelength of a sample.

DETAILED DESCRIPTION

The disclosure generally relates to a method and apparatus fordetermining illumination parameters for a sample. Having an a prioryknowledge of an optimal illumination wavelength for obtaining spectralimages of a sample is particularly important in that the appropriatewavelength enable simultaneous imaging of the sample at severalwavelengths. In one embodiment, the disclosure generally relates to amethod and apparatus for determining illumination parameters for asample. The illumination parameters enable, among others, simultaneoussignal detection from the sample. The detection mode can be selectedfrom the group consisting of wide field, Raman chemical imaging,multipoint, dispersive single point and dispersive line. The method andapparatus for obtaining simultaneous multi-mode images from a sample isdiscussed extensively in the co-pending patent application serial No.filed concurrently by the co-inventors named herein, the specificationof which is incorporated herein for background information.

FIG. 1 graphically illustrates the relationship between intensity andwavelength of a sample. The method of obtaining absorption andemissivity bands are conventionally known. It is also known thatemissive energy is associated with fluorescent imaging and absorptionenergy is associates with NIR. Thus, as a first step the sample isilluminated with photons of different frequencies. The illuminatingphotons (interchangeably, the detection photons) can include photonshaving wavelengths in the emission band and photons have wavelengths inthe absorption band. Moreover, the sample may be illuminated withphotons in a mode selected from the group including wide field, Ramanchemical imaging, multipoint, single point and line illumination.

Referring again to FIG. 1, line 125 represents the energy absorptionrelationship of a sample exposed to emissive and absorption bands. Peak130 represents the optimal intensity corresponding to absorptionwavelength (λabs-opt.) 125. The absorption energy band is considered toextend from a low frequency wavelength (λabs-L) to a high frequencywavelength (λabs-H). In FIG. 1, line 120 illustrates the relationbetween the intensity and wavelength of absorption energy of the sample.Peak 140 represents the emissive intensity peak (E_(m)) havingwavelength λE_(m). As with the absorption band, the emissivity intensityalso defines a bandwidth limited by lower and upper wavelengthsidentified as (λ_(Emis,L)) and (λ_(Emis,H)), respectively.

According to one embodiment of the disclosure an optimal wavelength forRaman spectroscopic imaging occurs at a wavelength just below or aboutthe low frequency range (λabs-low) of the absorption band. Oneembodiment of the disclosure relates to a method for definingillumination parameters for a sample by: (i) obtaining an absorptionband of the sample; (ii) obtaining an emission band of the sample, theemission band having a lower wavelength range (λabs-low) and an upperwavelength range (λabs-high); and (iii) assessing the illuminationparameters for the sample as a function of the absorption band and theemission band, and more specifically, as a function of the low frequencywavelength (λabs-low) of the sample. These steps cane be implementedsequentially or simultaneously. By way of example, this region is shownas 155 in FIG. 1. Thus, illumination parameter for the sample can beselected such that the parameters define a wavelength shorter than thewavelength of a peak in the emission spectrum. The illuminationparameters may also be used to define a laser line or a suitable Ramanwavelength.

In another embodiment, the optimal wavelength range for Raman can befound at about the region where the absorption bandwidth 130 and theEmission bandwidth intersect.

In FIG. 1 peak 150 represents Raman spectrum. Peak 1740 shows the peakof the emission spectrum and peak 130 shows the peak of the absorptionspectrum.

While the steps of obtaining absorption band and emission band can beimplemented sequentially, one embodiment of the disclosure relates toimplementing both steps substantially simultaneously. In this manner, amulti-mode image of a sample can be obtained substantiallysimultaneously.

Thus, according to one embodiment of the disclosure a method fordetermining illumination parameters for a sample includes:simultaneously illuminating the sample with illuminating photons. Theilluminating photons can have several different wavelengths or define abroad range of wavelengths. Next, the wavelengths for the emission bandand the absorption bands of the sample can be defined. In addition, theemission band and the absorption band can define the wavelength for thepeak intensity in each band as well as the lower and the upperwavelength ranges for each band. Using the lower wavelength of theabsorption band (λabs-L) an optimal Raman wavelength detectionwavelength for the sample can be defined as Raman scattered photonshaving wavelength about or below λabs-L. By way of example, one suchregion is shown as region 155 in FIG. 1. The illumination parametersthus obtained can be used to illuminate the sample with illuminatingphotons of different wavelengths to obtain simultaneous spectral imagesof the sample. The illuminating photons can be a laser line, wide-field,Raman chemical imaging, multipoint imaging, dispersive single point anddispersive lines specifically devised to be within the desiredwavelength range.

In a system according to one embodiment of the disclosure, theillumination parameter for a sample includes one or more illuminationsources, an optical train and a processor programmed with instructionsto simultaneously illuminate the sample with illuminating photons anddetect an emission band and an absorption band of the sample. Theinstructions can also include defining a lower wavelength range and anupper wavelength range for the band and determine the illuminationparameters for the sample as a function of the absorption and theemission bands of the sample. Finally, the instructions may includedefining a suitable Raman wavelength for the sample at a wavelengthshorter than the lower wavelength range of the emission spectrum.

While the principles of the disclosure have been disclosed in relationto specific exemplary embodiments, it is noted that the principles ofthe invention are not limited thereto and include all modification andvariation to the specific embodiments disclosed herein.

1. A method for determining an illumination parameter for a sample, themethod comprising: obtaining an absorption band of the sample; obtainingan emission band of the sample; and determining the illuminationparameter for the sample as a function of the absorption band and theemission band of the sample.
 2. The method of claim 1, wherein the stepof obtaining an absorption band of the sample further comprises the stepof illuminating the sample.
 3. (canceled)
 4. The method of claim 1,wherein a suitable Raman wavelength occurs at a shorter wavelengthdefined by the emission band of the sample.
 5. The method of claim 1,wherein the illumination parameter defines a laser line.
 6. The methodof claim 1, further comprising the step of illuminating the sample withphotons in a mode selected from the group consisting of wide field,Raman chemical imaging, multipoint, single point and line illumination.7. The method of claim 1, wherein the steps of obtaining an absorptionband and obtaining an emission band are implemented simultaneously. 8.The method of claim 1, wherein the steps of obtaining an absorption bandand obtaining an emission band are implemented sequentially.
 9. A systemfor defining illumination parameters for a sample comprising anillumination source, an optical train and a processor programmed withinstructions for obtaining an absorption band of the sample; obtainingan emission band of the sample, the emission band including a lowerwavelength range and an upper wavelength range; and determining theillumination parameters for the sample as a function of the absorptionband and the emission band of the sample.
 10. The system of claim 9,wherein the step of obtaining an absorption band of the sample furthercomprises illuminating the sample.
 11. The system of claim 9, whereinthe illumination parameters define a wavelength below than the lowerwavelength range of the sample.
 12. The system of claim 9, wherein asuitable Raman wavelength occurs at a wavelength below the lowerwavelength range of the sample.
 13. (canceled)
 14. The system of claim9, further comprising the step of illuminating the sample with photonsin a mode selected from the group consisting of wide field, Ramanchemical imaging, multipoint, single point and line illumination.
 15. Amethod for determining illumination parameters for a sample, the methodcomprising: simultaneously illuminating the sample with illuminatingphotons, the illuminating photons defining a first wavelength and asecond wavelength; obtaining at least one of an emission band and anabsorption band of the sample from the illuminating photons interactingwith the sample, the emission band defining a lower wavelength range andan upper wavelength range; and determining the illumination parametersfor the sample as a function of the absorption band and the emissionband of the sample.
 16. (canceled)
 17. (canceled)
 18. The method ofclaim 15, further comprising illuminating the sample with photons havingwavelength within the illumination parameters.
 19. The method of claim15, wherein the step of obtaining an absorption band of the samplefurther comprises illuminating the sample.
 20. (canceled)
 21. The methodof claim 15, wherein a suitable Raman wavelength occurs at a wavelengthshorter than the emission band. 22-32. (canceled)
 33. The method ofclaim 15 wherein the step of illuminating the sample with photons in amode selected from the group consisting of wide field, Raman chemicalimaging, multipoint, single point and line illumination.